Dual function detector device

ABSTRACT

A dual function detector device operates in either a normal operating mode or in an EMI correction mode to suppress effects of EMI within the detector. The detector device may be a flat panel x-ray detectors used in x-ray imaging systems. The device has a pixel architecture and panel read-out technique that enables real-time, high spatial frequency measurement of noise induced by electromagnetic radiation on a digital x-ray detector. The measurement can be used to calibrate the detector in real-time to attain artifact-free imaging in all environments, including those that contain temporally and spatially changing electromagnetic fields.

BACKGROUND

The invention relates generally to x-ray imaging systems. Moreparticularly, the present invention relates to improved x-ray detectorsand methods of operating the same.

In the field of diagnostic or medical imaging, flat panel digital x-raydetectors are routinely used. Flat panel digital x-ray detectorsgenerally provide higher image quality and improved processing time,image storage and image transfer over previously known x-ray filmtechniques. However, the digital x-ray detectors available today havehigh sensitivity and make the detector susceptible to electromagneticinterferences (EMI), and EMI is even more likely in portable detectorsystems. Unlike traditional table or wall stand x-ray systems thatoperate in designated x-ray rooms, portable units work almost everywherein the hospital. It has also been found that some hospital equipment andsystems interfere with the detector and generate artifacts in the x-rayimage.

Flat panel x-ray detectors are now used routinely for medical imaging.In the typical configuration, the detectors can be sensitive toelectromagnetic radiation produced in the local environment. Examples ofequipment that may produce electromagnetic radiation include CRTmonitors, catheter navigation systems, and surgical ablation devices.Temporally and spatially changing electromagnetic fields can inducephantom signals in the x-ray detector. These image artifacts can degradethe overall image quality of x-ray imaging system. Although shieldingcan be used to attenuate the amplitude of the electromagnetic radiation,this shielding will also attenuate the x-ray radiation and degrade theoverall image quality of the x-ray imaging system. The proposedinvention will reduce the sensitivity to electromagnetic radiationwithout reducing the x-ray sensitivity.

BRIEF DESCRIPTION

In accordance with a first aspect of the present invention, a detectordevice is provided and includes: at least one pixel having anphotodetector portion and a non-photodetector portion; a first line foroperably coupling to each of the portions of the pixel; a second linearranged to separate a middle of the at least one pixel, wherein thesecond line is not operably coupled to the at least one pixel; andwherein the first line is selectively enabled to selectively activatethe photodetector portion.

In accordance with a first aspect of the present invention, an x-raydetector device is provided and includes: a plurality of pixelsincluding a photodiode portion and a FET portion for receiving x-raysignals; at least one scan line coupled to at least a first portion ofthe pixels for selectively activating at least a first portion of thepixels; and, at least one data line for conducting charge indicative ofthe x-ray signals.

In accordance with a third aspect of the present invention, a method foroperating an x-ray detector is provided and includes: simultaneouslyacquiring image and electromagnetic inference (EMI) correction dataduring an acquisition; and operating the detector in either a normaloperating mode or in an EMI correction mode.

DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1, a perspective and block diagrammatic view of an x-ray imagingsystem utilizing a detector array or a flat-panel x-ray detector inaccordance with an embodiment of the invention.

FIG. 2 is a plan view of a typical pixel structure in a flat paneldigital detector.

FIG. 3 is a prior art figure of a typical flat panel x-ray detector thatincludes an array of 2D photosensitive diodes and switching transistors(FETS) arranged in rows and columns.

FIG. 4 is plan view of a portion of the flat panel detector shown inaccordance with an embodiment of the invention.

FIG. 5, a schematic and block diagrammatic view of an x-ray detectorpanel, formed of the pixel architecture shown in FIG. 4

FIG. 6 is a schematic of a pixel architecture of a portion of a detectorillustrating a double scan line configuration in accordance with anembodiment of the invention.

FIG. 7 is a schematic of a binned pixel architecture of a portion of adetector illustrating a double scan line configuration in accordancewith an embodiment of the invention.

FIG. 8 is a schematic of a binned pixel architecture of a portion of adetector with a 2×3 pixel unit cell illustrating an additional scan lineadded after every second row of pixels in accordance with an embodimentof the invention.

FIG. 9 is a schematic of a binned pixel architecture of a portion of adetector with a 3×4 pixel unit cell illustrating an additional scan lineadded after every second row of pixels in accordance with an embodimentof the invention.

FIG. 10 is plan view of a portion of a flat panel detector having dualdata lines shown in accordance with an embodiment of the invention.

FIG. 11 is a block diagram and schematic of a pixel architecture in adetector device having two data lines associated with each column ofpixels in accordance with an embodiment of the invention.

FIG. 12 is a schematic of a pixel architecture of a portion of adetector with a 1×2 pixel unit cell illustrating a double data lineconfiguration associated with every column of pixels in accordance withan embodiment of the invention.

FIG. 13 is a schematic of a binned pixel architecture of a portion of adetector with a 1×4 pixel unit cell illustrating a double data lineconfiguration associated with every column of pixels in accordance withan embodiment of the invention.

DETAILED DESCRIPTION

The invention relates to a pixel architecture and panel read-outtechnique that enables real-time, high spatial frequency measurement ofnoise induced by electromagnetic radiation on a digital x-ray detectorof the type used in x-ray imaging systems.

The effects of the electromagnetic radiation on digital x-ray detectors,i.e. electromagnetic interference (EMI) are a function of time, space,(i.e. the x-y coordinate on the flat panel), and detector design. Lowlevel electrical parameters associated with characteristics including,but not limited to resistance, capacitance, bandwidth, geometric sizeand shape associated with the pixel architecture cause coupling of theelectromagnetic field to the digital detector.

In an embodiment of the invention, a duplicate device structure forcollection of both EMI correction data and image data is used, whereinthe device structure includes not only pixels, but also the lines usedto address and read-out selected pixels including data lines, scanlines, a common electrode to associated read-out electronics, such as anapplication-specific integrated circuit (ASIC) in electrical signalcommunication with each data line, wherein the ASIC is used to read-outthe charge and convert it to a digital signal. The measurements obtainedusing the invention may be used to calibrate the detector in real-timeto attain artifact-free imaging in all environments, including thosethat contain temporally and spatially changing electromagnetic fields.

In the following figures, the same reference numerals will be used torefer to the same components. While the invention is described withrespect to x-ray detectors, corresponding x-ray systems, and methods foroperating each, the present invention is capable of being adapted forvarious purposes and is not limited to the following applications:computed tomography (CT) systems, radiotherapy or radiographic systems,x-ray imaging systems, and other applications known in the art. Thepresent invention may be applied to radiographic detectors,cardiographic detectors, or other detectors known in the art.

In the following description, various operating parameters andcomponents are described for one constructed embodiment. These specificparameters and components are included as examples and are not meant tobe limiting.

Referring now to FIG. 1, a perspective and block diagrammatic view of anx-ray imaging system 20 utilizing a detector array or a flat-panel x-raydetector 32 in accordance with an embodiment of the present invention isshown. The system 20 includes an x-ray source 24 that generates an x-raybeam 26, which is directed to pass through a region-of-interest 28 of apatient 30. The beam 26 is attenuated by an internal structure of thepatient 30 and is received by the detector 32. The system 20 may operatein two modes including a normal operating mode that does not suppressEMI and an EMI suppression mode that simultaneously reads the paneldetector 32 at a slower speed than normal operation and also correctsfor EMI occurring by obtaining EMI offset data within the detector 32.Thus, the system 20 provides a dual function x-ray detector capable ofoperating in a normal operation mode or in an EMI correction mode inaccordance with multiple embodiments of the invention.

A method of using the detector 32 to eliminate EMI is disclosed withreference to FIGS. 6-9, and 10-13 in accordance with several embodimentsof the invention.

In an embodiment of the invention, image data and EMI correction dataare simultaneously collected in contrast to existing methods, asdiscussed herein, that do not collect correction data simultaneously,but rather at an earlier or later time than the image data is collected.In an embodiment of the invention, EMI correction data is acquired at ahigh spatial frequency, that may be less than 2 cm such as, but notlimited to 100 um across the entire active area of the flat paneldetector 32.

The EMI offset correction enables the x-ray detector to operate in aplurality of modes, wherein one mode includes EMI correction thatoperates to suppress EMI from the detector and another mode does notinclude EMI correction.

A typical flat panel x-ray detector includes an array of 2Dphotosensitive diodes and switching transistors (FETs) arranged in rowsand columns. A portion of the flat panel detector 32 depicted in FIG. 1is shown in FIG. 3; the detector 32 is made from a plurality of pixelsas shown in more detail in FIG. 2. Scan lines are provided to controlthe switching of the transistors, and data lines are provided to conductthe signal from the array to the readout electronics. Typically, thedata lines all have FETs connected on every row of the array. When ascan line is energized and switches on a row of FETs, the x-ray signalis simultaneously read out in parallel to data conversion electronics.Data from an entire image is read out by sequentially reading out allthe rows of the detector.

Generally, as is well-known and will only be described briefly herein, adigital x-ray detector commonly has an array of pixels composed of fieldeffect transistors (FETs) 146 that perform as switches and photodiodes148, to detect light in a known manner. The FETs 146 and the photodiodes148 are constructed of, for example, amorphous silicon, over whichcesium iodide (CsI) or other known materials is deposited. The CsIabsorbs x-rays, generated by an x-ray source, and converts them intolight energy, which is then detected by the photodiodes 148. Thephotodiodes, due to their construction, perform as capacitors and storeenergy in the form of a charge.

Referring to FIG. 2, a plan view of a typical pixel structure 132 in aflat panel digital detector such as the detector 32 shown in FIG. 3 isshown. FIG. 2 illustrates a single pixel within a typical flat panelx-ray detector and includes one scan line 134 and one data line 136.Each FET 146 is associated with a photodiode 148 and includes a gateterminal 150, a drain terminal 152, and a source terminal 154.

The photodiode 148 has a cathode 156 and an anode 158. The cathode 156is coupled to the source terminal 154 of the FET. As shown in moredetail in FIG. 3, the anode 158 is coupled to a voltage source 160 at acommon electrode 162 and has a common electrode voltage potential. Thevoltage source 160 is coupled to a common ground 164. Assuming that theFET 146 performs as an ideal switch, voltage potential across thephotodiode 148 formed by the difference in potential between the dataline potential, and the common voltage potential, may be referred to asthe photodiode bias.

The scan and data lines may be continuous across the entire panel or maybe cut once (typically in the middle) and are connected to externalelectronics at the edge(s) of the panel as disclosed in U.S. PatentPublication 2005/0121616 A1, the disclosure of which, includingreferences cited therein, is herein incorporated by reference.Typically, a single pixel forms a unit cell that is repeated across theentire panel and thus all pixels are designed to be substantiallyidentical.

As disclosed in U.S. Patent Publication 2005/0121616 A1, which is hereinincorporated by reference, the detector may have a split design with aleft half having pixels coupled to a first drive circuitry and a righthalf having pixels coupled to a second drive. Each pixel in the lefthalf is coupled to a common data line with a pixel in the right half.Each of the halves and have corresponding sets of pixels, scan lines,and data lines, some examples of which are stated below. There may beany number of sets and the sets may be of various sizes. The scan linesare split such that the pixels in the left half are coupled to the scandrivers of the first drive circuitry and the pixels in the right halfare coupled to the scan drivers of the second drive circuitry. Varioussequential read-out techniques may be used to read each selected orselected groups of pixels.

FIG. 4 is plan view of a portion of a flat panel detector 33 such as thedetector shown in FIG. 1 accordance with an embodiment of the invention.

In an embodiment of the invention shown in FIG. 4, additional scan linesor data lines are added to increase the unit cell to larger than asingle pixel.

Although the adjacent scan lines, such as scan lines 40 a, 40 b areshown as being spaced apart from each other, the adjacent scan lines maybe “stacked” on top of each other so as to maximize the photodiode fillfactor. When the adjacent scan lines are stacked, the adjacent stackedscan lines are spaced apart or separated by an insulating material, in adirection orthogonal to the plane of the detector 33. The separation orinsulating material assures that there is not a conductive connectionbetween the adjacent scan lines, similar to the separation between thescan lines 40, shown in FIG. 1, that are not stacked.

During operation of the detector 33, the pixel unit cells 60 are scannedby scanning circuitry 38 (shown in FIG. 1), via scan lines 40, togenerate exposure data.

Each cell 60 independently measures intensity of the x-ray radiationreceived over a corresponding pixel exposed area or photodiode area togenerate the exposure data. The exposure data is received and digitizedby readout electronics or circuitry 42 through use of the data lines 44(shown in FIG. 1).

As shown in FIG. 4 a scan lines 40 a, 40 b operates to energize the FETs62 a, 62 b, respectively, when powered or energized. Referring now toFIG. 4, block diagrammatic view of the pixel unit cell 60 is shown inaccordance with an embodiment of the invention. The pixel unit cell 60has two pixels 60 a (shown in FIG. 4 on a left side of pixel unit cell60), and 60 b (shown in FIG. 4 to the right of pixel 60 a) eachincluding a respective photodetector portion such as a photodiode 64 a,64 b (shown as a top and a bottom portion of photodiodes 64 a, andphotodiode 64 b, respectively) associated with pixels 60 a,60 b and anonphotodetector portion, wherein the pixels 60 a, 60 b of the pixelunit cell 60 are coupled to at least two lines selected from a scan line40 a or 40 b that activates the non-photodetector portion such as theFETs 62 a, 62 b. The FET location defines the pixel unit celldimensions, wherein the pixel unit cell is the smallest structure thatis repeated within the detector array. As shown in FIG. 4, each FETwithin the unit cell 60 is attached to every other scan line. The FET 62a associated with a pixel 60 a attaches to scan line 40 a, and the FET62 b associated with pixel 60 b is relocated within the pixel 60 b(shown in the middle of pixel 60 b in FIG. 5) to connect with scan line40 b. The two pixels 60 a, 60 b define a 2×1 pixel unit cell. Anadditional scan line 40 b is added to attach to a selected number ofFETs associated with a selected number of pixels, wherein the selectednumber of FETs are moved to a different location within the pixel tofacilitate connection with the additional scan line.

The new scan line 40 b that runs through a portion of the pixel unitcell 60 reduces the potential of shorts between the respective scan ordata lines. In order to minimize the capacitance of the new scan or dataline and the capacitive coupling to each photodiode, the photodiodematerial above the new scan line 40 b is eliminated. Each splitphotodiode 64 a, 64 b includes an associated conductive bridge 82 a, 82b, respectively or contact linking the cathodes 74 a, 74 b of each ofthe split photodiodes together. The conductive bridge 82 a, 82 bincludes a conductive material such as a metal and connects two portionsof each photodiode 64 a, 64 b across the additional scan line 40 b. Anadditional via 65 a, 65 b, respectively connects a common electrode 76to both portions of each the split photodiodes 64 a, 64 b, respectively.

Referring now to FIG. 5, a schematic and block diagrammatic view of anx-ray detector panel 33, formed of the pixel architecture shown in FIG.4 having double scan lines 40 b, wherein scan line 40 b splits eachpixel diode 64 a, 64 b in to two portions and data lines 44 eachassociated with selected pixel unit cells 60, in accordance with anembodiment of the present invention is shown. A selected portion ofpixels 60 a, 60 b includes split photodiodes 64 a, 64 b, respectively inhalf by either an associated scan line 40 b, wherein the two photodiodes64 a, 64 b are each coupled in parallel with a common electrode 76connected to a respective anode 84 a, 84 b of each photodiode 64 a, 64b, respectively. The common electrode 76 is further connected to avoltage source 80.

As shown in FIG. 5, every other pixel 60 includes respective fieldeffect transistors (FET) 62 associated with the split diodes 64 a, 64 b.Each FET 62 arranged in an alternating pattern includes a gate terminal70, a drain terminal 72, and a source terminal 75. Thus, every otherpixel 60 includes a FET 62 associated with the split diodes 64 a, 64 b.

In an embodiment of the invention shown in FIG. 5, twice the number ofscan lines 40 are provided since each FET associated with each pixelportion 60 a, 60 b is coupled to an associated first scan line 40 a anda second scan line 40 b, respectively.

A first set of scan lines 40 a are coupled between the gate terminals 70of selected FETs and the drive or scanning circuitry 38 and operate toactivate each of the 64a pixels when energized. A second set of scanlines 40 b are coupled to a set of selected FETs not connected to thefirst set of scan lines 40 a and activate each of the 64b pixels whenenergized. The data lines 44 are coupled between the drain terminals 72of selected FETS and the readout electronics of the readout electroniccircuitry 42.

The scan lines 40 a, 40 b are used to activate selected FETs within arow or a row segment and to simultaneously allow correspondingphotodiodes within a particular row or row segment to charge. The datalines 44 are used to discharge the photodiodes 64, thereby collectingexposure or offset data therefrom. The data lines 44 are used by readoutcircuitry 42 to read the amount of charge discharged from thephotodiodes 64. As each scan line 40 a, 40 b is activated, each dataline 44 has an associated readout channel (not shown) from which theacquisition processing circuit 48 or readout circuitry 42 receives theexposure data, from the photodiodes 64 a, 64 b, within each pixel unitcell 60 on an associated activated scan line, are simultaneouslyrestored to an initial charge.

Referring now to FIGS. 1 and 5, the voltage across the photodiodes 64 ofeach pixel unit cell is generally controlled by the bias circuitry 46.The photodiode common bias or electrode circuitry 46 is electricallycoupled to the detector 32, 33 and controls the anode voltage of thepixel unit cells 60.

A controller 50 is electrically coupled to both the readout circuitry 42and the scan circuitry 38. The controller 50 controls the order andspeed of readout, as well as the photodiode common bias voltage.Although, the controller 50 is shown as being part of the readoutcircuitry 42 it may be part of other circuitry, such as the photodiodecommon bias circuitry 46, the scan circuitry 38, or the acquisitioncontrol and image processing circuit 48. The controller 50 iselectrically connected to the common electrode 76. The controller 50 maychange the common electrode potential in accordance with the desiredapplication. The potential of the common electrode 76, which effects andis directly related to the photodiode bias, is controlled by thecontroller 50.

The bias voltage to which the split photodiodes 64 a, 64 b are chargedis equal to the difference between the voltage level of the commonelectrode 76 and the voltage level of a respective photodiode data line.In order for the photodiodes 64 a, 64 b to store a capacitive charge,they are reverse biased, such that each photodiode anode 84 a, 84 b ofeach split photodiode 64 are coupled to the common electrode 76, whichhas a voltage potential that is more negative than that of the datalines 44.

An acquisition control and image processing circuit 48 is electricallycoupled to the x-ray source 24, the scanning circuitry 38, the readoutcircuitry 42, and the bias circuitry 46 and coordinates operationthereof. The acquisition control and image processing circuit 48reconstructs an image 34 in response to the exposure data, which isdisplayed on the monitor 36.

The acquisition control and image processing circuit 48 and thecontroller 50 may be microprocessor based, such as a computer having acentral processing unit, memory (RAM and/or ROM), and associated inputand output buses. The processing circuit 48 and the controller 50 maysimply be formed of logic state machines or of other logic devices knownin the art. The processing circuit 48 and the controller 50 may be aportion of a central main control unit, an electronic control module, ormay each be stand-alone controllers, as shown.

A plurality of similarly formed pixel unit cells 60 may be arranged inalternating patterns to form a plurality of pixel unit cells that may beselectively enabled to activate the photodetector portion and todetermine an EMI correction data offset value.

Referring now to FIGS. 1 and 5, the detector 33 is divided into multiplepixel unit cells 60 that include read pixels or sub-pixels, that areread out to readout electronics by an associated data line andcalibration pixels that provide calibration data to determine EMIcorrection data (ECD). Depending on which scan line is energized, eachpixel may be a read pixel or a calibration pixel. Each pixel unit cell60 is a smallest geometry of one or more pixels associated with arepeating pattern of read pixels and calibration pixels, wherein thepitch of each pixel unit cell 60 is equal to a largest dimension of agroup of repeating pixels in a linear x or y direction. The pitch ofeach EMI correction data pixel (ECD) is equal to the number of scanlines multiplied by a minimum predefined pitch of each pixel. In anembodiment of the invention, a distance between two adjacent scan linesis defined the pixel pitch.

A portion of selected detectors having varying pixels unit cells inaccordance with several embodiments of the invention are shown in FIGS.6-9, and 12-13, the detector 33 may have any number of pixels unit cellsranging in dimension of M by N defining a number of individual pixelsper pixel unit cell, wherein M is a positive integer defining a numberof individual pixels per row or row segment and N is a positive integerdefining a number of individual pixels per column.

Each data line is connected via an associated FET and diode pixels toselected portions of pixels in the data line's associated column.Similarly, each scan line is connected via associated FETs to a portionof the pixels in an associated row. Since every pixel on the row must beconnected to a scan line in order to function properly, the remainingpixels must be connected to one of the adjacent scan lines.

Both the even and the odd data lines have substantially equivalentstructures and characteristics including, but not limited to resistance,capacitance, geometric shape and size, optical reflectivity, material,and wherein the number of FET's attached to the even and odd data linesand are closely spaced apart.

In an embodiment of the invention, a total number of n+1 scan lines foreach set of rows having pixels forming a repeating pixel unit cell mayadded at every n number of rows defining respective pixel unit cells,wherein n is a positive integer. A plurality of pixel unit cells arearranged in a repeating pattern, wherein each unit cell is defined by nby m pixels, and wherein n defines a number of rows and m defines anumber of columns associated with each unit cell. EMI correction data isobtained at every n+1 pixel as described in more detail below.Additionally, the pitch of the panel including EMI correction data isthe minimal number of scan lines needed to activate the selected pixelunit cell multiplied by a minimal predefined pitch.

In an embodiment of the invention, a non-operational (“dummy”) scan lineis added through each row of pixels that does not have an operationaladditional scan line. Addition of the dummy scan lines allows each pixelin the detector array to have substantially similar characteristics andthus, to avoid spatially correlated image artifacts. Dummy scan linesassure that each pixel will have similar low level characteristicsincluding, but not limited to overall capacitance, capacitive couplingcoefficients, fill factor, light collection efficiency, and lag.

When running in a normal EMI correction mode, an increased number ofscan line connections and electronics are needed and the panel read-outrate is reduced for each additional scan line added. However, the panelread-out rate may be reduced by selectively energizing individual orgroups of scan lines and by selectively reading out individual or groupsof pixels unit cells.

The readout time for a detector panel having a predefined minimum pixelpitch X, wherein the detector panel has n rows and n+1 scan linesassociated with repeating patterns of pixels forming repeating pixelcells. The pixel pitch X of the detector panel is multiplied by a scalarfactor equaling n+1/n to determine an actual panel readout time rate((n+1/n)*X) when EMI correction occurs.

In an embodiment of the invention, the detector operates in an EMIdetection mode when each scan line is separately energized, after afirst scan line is energized, the image acquisition sequence continueswhen each subsequent scan line after the first scan line is sequentiallyand selectively energized and then each pixel or pixel unit cell isselectively and sequentially read by respective data lines.

When the detector is not operating in an EMI detection mode, but rather,a normal, non-EMI detection mode (normal operating mode), the operationof the detector may be the same as a detector that does not haveadditional scan lines through use of selective activation of one or morescan lines and data lines to energize and read the pixels or sets ofpixel cell units in the detector. When operating in a normal mode, thenumber of scan lines simultaneously energized at one time duringsequential reading of the detector is equal to n+1, wherein EMIcorrection occurs at every n+1 pixel, if n+1 pixels are read when n+1scan lines are activated, the EMI correction pixels are activated andread out on the data lines as a read pixel and no EMI calibration datais provided. Thus, for EMI correction to occur, no more than n scanlines may be simultaneously energized at one time per panel read.

In an embodiment of the invention, whether the detector is operating inan EMI correction mode or a normal mode, a minimum number of data linesthat are simultaneously in a sequential manner across a selected portionof pixels during each scanning event equals n+1. Thus, if EMI correctionoccurs at every n+1 pixels, during activation of each scan line per rowor groups of row, n+1 groups of data lines read out data from each n+1pixel cell unit.

In an embodiment of the invention shown in FIGS. 6-7 includes a portionof a detector capable of operating in either a normal mode or an EMIcorrection mode. The detector includes twice as many scan lines as shownin FIG. 2.

FIG. 6 is a schematic of a pixel architecture of a portion of a detectorillustrating a double scan line configuration in accordance with anembodiment of the invention.

In an embodiment shown in FIG. 6, a portion of a detector display 300 isshown having a plurality of pixels 304 arranged in every other column,and a plurality of pixels 306 arranged in every other column adjacent tothe 304 pixels. For example purposes, the pixel unit cells of thedetector are arranged rectangularly in rows or row segments and columns,of course other arrangements may be used. Each row or row segment isdesignated by scan lines and each column is designated by data lines.

A plurality of FETS are associated with each of the pixels 304 and 306.Every other FET, illustrates as enlarged black rectangles, has beenmoved to a new scan line, thereby resulting in a 1×2 pixel unit cell 330that is repeated over the entire panel. The two scan lines per row ofpixels form a 1×2 pixel unit cell.

A plurality of pixels arranged in each row alternate between pixels 304and 306, wherein pixels 304 are odd pixels and are located on the odddata lines (Data lines 1, 3, . . . m, wherein m is an odd integer) andthe odd scan lines, and the even pixels 306 are located on the even datalines (Data lines 2, 4, . . . n, wherein n is an even integer) and theeven scan lines. Pixels 304 are each formed from the following sets ofpixel portions: 304 a 1 and 304 a 2; 304 b 1 and 304 b 2; 304 c 1 and304 c 2; and 304 d 1 and 304 d 2 respectively. Similarly, pixels 306 areeach formed from the following sets of pixel portions: 306 a 1 and 306 a2; 306 b 1 and 306 b 2; 306 c 1 and 306 c 2; and 306 d 1 and 306 d 2respectively.

As shown in FIG. 6, each of the pixels are further associated with aparticular row segment and are activated by an associated scan line. Forexample pixel 304 formed by pixel portions 304 a 1 and 304 a 2 islocated in row segment a1 and is activated by scan line a1.

Each row or row segment is either activated by an even scan line or anodd scan line. Each row having a second scan line splitting thephotodiodes in the row is made of two row segments, shown in FIG. 6 asfollows: Row A is defined by row segments a1 and a2, Row B is defined byrow segments b1 and b2, Row C is defined by row segments c1 and c2, andRow D is defined by row segments d1 and d2. An unlimited number of rowsz may be defined by segments z1 and z2, wherein z1 is associated withand activated by an odd scan line and z2 is associated with andactivated by an even scan line.

When the odd pixels 304 are activated by an odd scan line, the oddpixels are the read pixels and even pixels are the calibration pixels.Similarly, when the even pixels 306 are activated, the even pixels arethe read pixels and the odd pixels are the calibration pixels.

In an embodiment of the invention when the detector is operating in anEMI correction mode, each scan line is sequentially and consecutivelyenergized. When operating in this mode, the detector operates at halfthe detector's normal operating speed, thus the panel read out ratedecreases to half the rate associated with a normal panel read out andprovides real-time EMI correction data at every other pixel locationacross the entire active area.

In an embodiment of the invention, the pitch of each EMI correctionpixel unit cell 330 equals the number of scan lines necessary toactivate a pixel unit having a repeating pattern, wherein in FIG. 6, thenumber of scan lines is two lines multiplied by a minimal predefinedpitch. In an embodiment of the invention, the predefined pitch equals200 um, thus the pitch of the EMI correction pixel unit cell equals 400um.

When operating in the EMI correction mode, as described with referenceto FIG. 6, the first scan line is energized, and the odd pixels 304,which are connected by FETs to the odd data lines (data lines 2, 4, 6 .. . a, wherein a is a positive even integer), are discharged and theimage signal including EMI distortion is read-out on the odd data linesby the readout electronics. Since the even pixels 306 do not have FETsconnected to the odd scan lines, the signal on the even data lines (datalines 1, 3, 5, . . . b, wherein b is a positive odd integer) isgenerated by EMI and an offset signal, wherein the EMI and offset signalhas an offset related to charge leaking out of each of the associatedFETs connected to a respective data line in addition to a signalgenerated by EMI charge substantially originating from other FETsconnected to the same associated even data line.

Thus, signal from even data lines represents the EMI pick-up only fromthe EMI data or the offset corrected data. The EMI signal transmittedalong the even data lines is measured simultaneously with the imagesignal transmitted along the odd data lines. Each data line reads thepixels in sequential order individually or as sets of pixels (pixel unitcells), wherein individual or groups of data lines are simultaneouslyread out to the readout electronics. Once each pixel or pixel unit cellis read, the pixel is reinitialized to an initial state.

In an embodiment of the invention, an offset value is determined fromEMI calibration data sensed along a data line when no x-rays illuminatethe panel or portions of the panel, wherein when no x-rays areilluminated the FETs associated with pixels that are sensed are off. Astandard offset correction is determined by subtracting the signal readfrom the data line when no x-rays illuminate from the signal read fromthe same data line when the x-ray image illuminates the panel at anearlier or at a later time than when the x-rays do not illuminate thepanel. The offset correction represents the EMI only contribution to thesignal on an associated data line. The offset corrected data from offsetvalue along an associated data line may be used to correct the EMI fromthe image data read out along the associated data line. In oneembodiment of the invention, the EMI data from two adjacent data linesis averaged to remove an EMI signal gradient.

In another embodiment of the invention, EMI data from more than twoadjacent data lines is used to remove both the EMI signal gradient andto reduce the extra electronic noise associated with the EMI correctionprocess. Statistical methods such as, but not limited to a least squaresfit method or interpolation may be employed to obtain a low noise EMIcorrection data at a desired pixel or pixel unit cell.

In an embodiment of the invention, an alternative arrangements of FETsmay be arranged such that the odd pixels and the even pixels aretransposed. The panel having the alternative pixel architecture wouldoperate in a similar manner to the panel shown in FIG. 6.

To increase uniformity in the EMI detection and prevention, alternativearrangements of the FETs, called binning, may be made achieve optimalEMI correction by providing for uniform spatial frequency of the EMIcorrection pixels. Additionally, when operating in a binning mode, theread-out speed along the data lines is increased.

In an embodiment of the invention, FETs are placed along n+1 number ofscan lines (wherein n equals a total number of rows for a desiredrepeating pattern of FETs) such that so that the pixels within thedetector are binned to include an EMI correction pixel at every n+1pixels. When pixels are corrected at every n+1 pixel, special frequencyof EMI correction pixels is optimal.

FIG. 7 is a schematic of a binned pixel architecture of a portion of adetector illustrating a double scan line configuration in accordancewith an embodiment of the invention. More particularly, FIG. 7 is ablock diagram of a portion of a detector 302, wherein the pixels 304,306 are arranged in a checkerboard pattern such that pixels 304 and 306alternate with every column and row. The checkerboard pattern providesoptimal arrangement of the pixels to achieve optimal EMI correction byproviding for uniform spatial frequency. The architecture of the pixelsshown in FIG. 7 provides a symmetrical distribution of pixels, whereinthe spatial resolution of the detector is cut in half in one dimension.

In another embodiment of the invention, in addition to the arrangementof the pixels, binning may be performed by selectively activating scanlines to allow for desired panel read out speeds when in both the EMIcorrection mode or in the normal operating mode.

As shown in FIG. 7, the odd scan lines are depicted as scan lines a1,b1, c1, . . . Ro, wherein Ro corresponds to a particular odd row number,and the even lines are depicted as scan lines a2, b2, c2, . . . Rewherein Re corresponds to a particular even row number.

In an embodiment of the invention when operating in an EMI correctionmode, scan line a1 is energized and activates each of the 304 pixels(formed from pixel portions 304 a 1 and 304 a 2, respectively) in Rowa1, which are read by associated data lines to the readout electronics.When row a2 is activated, each of the 306 pixels (formed from pixelportions 306 a 1 and 306 a 2, respectively) read out calibration dataused to correct EMI offset in the 304 pixels formed from pixel portions304 a 1 and 304 a 2, respectively to the data lines. Each subsequentscan line (scan line b1, scan line b2, . . . scan line Ro, scan line Re)is then activated sequentially and correction continues in a likemanner, wherein the panel read out rate is decreased by half due todouble the number of scan lines that are energized and the pixels thatare then read by the data lines.

In another embodiment of the invention, when operating in a binned EMIcorrection mode, as shown in FIG. 7, either two odd or two even scanlines are simultaneously energized to bin signals in adjacent rows. Asshown in FIG. 7, two sets of each pixels 304 (for example, 304 a 1 and304 a 2; and 304 b 1 and 304 b 2) and 306 (for example, 306 a 1 and 306a 2; and 306 b 1 and 306 b 2) form a 2 by 2 pixel unit cell 332 due tothe arrangement of the FETs associated with each of the pixels in atwo-dimensional 2 by 2 pixel, respectively pattern. In a binned EMIcorrection mode, EMI correction data is still obtained from every othercolumn, as it is in the embodiment shown in FIG. 6, but the detector canread at an original panel read rate of 1× because only half of thepixels in each row are read by associated data lines.

In the binned EMI correction mode shown in FIG. 7, initially, two oddscan lines (scan lines a1, and b1) are energized simultaneously toenergize and bin the signal from pixels 304 that are located adjacentand diagonally from each other, wherein energized scan line a1 activatespixels 304 a, each formed from pixel portions 304 a 1 and 304 a 2, andwherein energized scan line b1 activates pixels 304 b formed from pixelportion 304 b 1 and 304 b 2. When pixels 304 a and 304 b are activated,then data from the pixels is read out on associated data lines to thereadout electronics and EMI correction data is read out on associateddata lines from pixels 306 a and 306 b. Once the two odd scan lines areread, the next sequential two even scan lines (scan lines a2, and b2)are energized simultaneously to energize and bin the signal from pixels306 that are located adjacent and diagonally from each other, whereinenergized scan line a2 activates pixels 306 a, each formed from pixelportions 306 a 1 and 306 a 2, and wherein energized scan line b2activates pixels 306 b formed from pixel portion 306 b 1 and 306 b 2.When pixels 306 a and 306 b are activated, then data from the pixels 306a and 306 b is read out on associated data lines to the readoutelectronics and EMI correction data is read out on associated data linesfrom pixels 304 a and 304 b.

Each subsequent sets of odd and even scan lines (scan lines c1, scanline d1, scan line c2, scan line d2 . . . scan line Ro, scan line Ro+1,scan line Re, scan line Re+1,) are then activated sequentially andcorrection continues in a like manner, wherein the panel read out rateis 1× due the simultaneous reading of two sets of scan lines at a time.

In the binned normal operation mode for detector portion 302, shown inFIG. 7, four adjacent scan lines (scan lines a1, a2, b1, and b2)associated with the 4-pixel unit cell 332 are energized at once, therebyreading the panel at twice the original read-out speed, 2×, with halfthe resolution, and with no EMI correction data.

However, all the modes of operating and reading the panel available forthe symmetrical double scan line arrangement shown in FIG. 7 are notavailable for pixel designs where additional scan lines are added morethan every other row in combination with asymmetrical groupings ofpixels across the panel.

FIG. 8 is a schematic of a binned pixel architecture of a portion of adetector with a 2×3 pixel unit cell illustrating an additional scan lineadded after every second row of pixels in accordance with an embodimentof the invention.

In the embodiment shown in FIG. 8, a portion of a detector display 312is illustrated. For every n rows, n+1 scan lines are provided. Thedetector display portion 312 adds an additional scan line after everysecond row, wherein n number of rows equals 2, and wherein the number ofscan lines equals n+1, or 3. Thus, for every two rows, (n equals 2) ofrepeating pixel patterns, 3 scan lines (2 plus 1) are needed to activateevery two rows. A 2×3 pixel unit cell (2 rows by 3 columns) 334 andprovides EMI correction data at every third pixel when operating in anEMI correction mode. The addition of the additional scan line everysecond row decreases the panel read-out rate to 3 scan lines per every 2rows or 1.5× slower than the original panel read out rate. The pitch ofpixel unit cell used in an EMI correction mode in FIG. 8 equals 3 scanlines multiplied by a minimal predefined pitch of an individual pixel.In an embodiment of the invention, the pitch of an individual pixel is200 um, and thus, the pitch of the cell 334 is 3 scan lines times 200um, or 600 um.

Referring now to FIG. 8, the detector display portion 312 includespixels 314, 316, and 318 arranged in repeating patterns across two rowsand three columns as shown in pixel unit cell 334. An additional scanline is added after every other row, thereby splitting every other rowof the detector portion 312 into two row segments shown in FIG. 8. Anunlimited number of rows may be defined by a repeating pattern ofnon-split rows, in combination with split rows in between each non-splitrow. A first and second scan line activates the non-split row, and thesecond and a third scan line activate the split rows.

As shown in FIG. 8, a first set of pixels 314 and 318 is arranged in arepeating pattern of two pixels 314 and one pixel 318 on selected rows,wherein pixels 314 are associated with a first respective scan line(scan lines a, and c, respectively), and pixels 318 are associated witha second respective scan line (scan lines b1 and d1, respectively)adjacent to the respective first scan line (scan lines a, and c,respectively), a second set of pixels 316 and 318 are arranged in arepeating pattern on selected rows associated with two scan lines,wherein pixels 318 are associated with the second scan line (scans lineb1, and d1, respectively) adjacent to the first scan line (scan lines a,and c, respectively), and wherein pixels 316 are associated with a thirdscan line (scan lines b2 and d2, respectively) adjacent to the secondscan line (scan lines b1, and d1, respectively). The third scan line(scan lines b2 and d2, respectively) splits the pixels 316 and 318 inhalf, and thus splits every other row into row segments.

A plurality of FETS are associated with each of the pixels 314, 316, and318. Each FET, illustrated as enlarged rectangular dots within aparticular pixel, respectively associated with each pixel 314, 316, and318 are each associated with a particular scan line. As illustrated inFIG. 8, pixels 314 are associated with the first scan line (scan line a,and c, respectively), pixels 318 are associated with the second scanline (scan line b1, and d1, respectively), and pixels 316 are associatedwith the third scan line (scan line b2, and d2, respectively).

The repeating arrangement of the pixels 314, 316, and 318 forms the 2×3pixel unit cell 334 that is repeated over the entire panel, wherein therows a and c are not split by a scan line, but the rows b and d aresplit by a scan lines, thus forming row segments b1 and b2, and d1 andd1, respectively. Row segments b1 and b2 form row b, and row segments d1and d2 form row d. Rows a and c are activated when scan lines a and care energized. Rows b and d are selectively activated, respectively whenboth scan lines b1 and b2, and when both scan lines d1 and d2,respectively are selectively activated.

Row segments b1 and d1 are selectively activated, respectively when scanlines b1, and d1 are selectively activated, and row segments b2 and d2are selectively activated when scan lines b2, and d2, respectively areselectively activated.

In an embodiment of the invention, the detector portion 312 operates ina binned normal, non-EMI correction mode (binned normal mode). Whenoperating in the binned normal mode, two rows are activatedsimultaneously by three adjacent scan lines. As shown in FIG. 8, tosimultaneously activate adjacent rows, a, b, and c, d, respectively,three scan lines a, b1, and b2, associated with rows a and b, and threescan lines c, d1, and d2, associated with rows c and d, respectively aresimultaneously energized. The readout rate of the panel would be 1× ofthe original panel readout rate due to three rows being read with only athird of the data total being read from each of the three rows.

When the detector portion 312 operates in an EMI correction mode, eachscan line is activated separately. Thus, scan lines a, b1, and b2 areactivated separately, and are each simultaneously read out on each setof three data lines (1-3, 4-6, . . . dataodd-dataodd+2,dataeven-dataeven+2) that correspond to the pixels within each pixelunit cell 334. When selectively activating scan lines a, and c, each setof repeating pixels forming pixel cell 334 of the pixels in each row areread to three sets of data lines, the pixels 314 a in row a are read todata lines 1 and 2, and pixels 318 are read to data line 53 to providecalibration data for pixels 314 a when scan line a is energized, andpixels 314 c in row c are read to data lines 1 and 2, and pixels 318 care read to data line 3 provide calibration data for pixels 314 c whenscan line c is energized, respectively. Similarly, when selectivelyactivating scan lines b1, and d1, respectively, pixels 318 formed frompixel portions 318 b 1 and 318 b 2 associated with in row segment b1 areread to every third data line (data line 1, data line 4) and pixels 316formed from pixel portions 316 b 1 and 316 b 2 associated with rowsegment b1 are read to every other two data lines (data line 2, dataline 3, and data line 5, data line 6) to provide calibration data forpixels 318, and pixels 318 formed from pixel portions 318 d 1 and 318 d2 associated with row segment d1 are read to every third data line (dataline 1, data line 4) and pixels 316 (formed from pixel portions 316 d 1and 316 d 2) are read to every other two data lines (data line 2, dataline 3, and data line 5, data line 6) to provide calibration data forpixels 318 associated with row segment d1. When selectively activatingscan lines b2, and d2, pixels 316 (formed from pixel portions 316 b 1and 316 b 2) associated with row segment b2 are read to every other twodata line (data lines 2-3, and data lines 5-6) and pixels 318 associatedwith row segment b2 are read to every third data lines (data line 1, anddata line 4) to provide calibration data for pixels 316 associated withrow segment b2, and pixels 316 (formed from pixel portions 316 d 1 and316 d 2) associated with row segment d2 are read to every other two datalines (data lines 2-3, and data lines 5-6) and pixels 318 associatedwith row segment d2 are read to every third data lines (data line 1, anddata line 4) to provide calibration data for pixels 316 associated withrow segment d2.

However, all the modes of operating and reading the panel available forthe double scan line arrangement shown in FIGS. 6-7 are not availablefor the 2×3 pixel unit cell design.

In an embodiment of the invention, shown in FIG. 8, a 2×3 pixel unitcell design is shown. The panel having the 2 by 3 pixel cell arrangementcannot be read at an original speed and resolution, wherein an originalspeed and resolution is the read out speed and resolution of thedetector that occurs when no EMI correction data is present.Additionally the panel shown in FIG. 8 cannot be run in a binned modewith EMI correction data because of the asymmetric arrangement of thepixels and scan lines throughout the panel. However, a 2-row binned modewith no EMI correction having the pixel architecture shown in FIG. 8 maybe performed using the panel arrangement shown in FIG. 8, thus allowingthe detector to read at a normal 1× operating speed.

In an embodiment shown in FIG. 9, a portion of a detector display 320 isillustrated. FIG. 9 is a schematic of a pixel architecture of a portionof a detector with a 3×4 pixel unit cell illustrating an additional scanline added after every second row of pixels in accordance with anembodiment of the invention. For every n rows, n+1 scan lines areprovided. The detector display portion 320 adds an additional scan lineafter third row, wherein n number of rows equals 3, and wherein thenumber of scan lines equals n+1, or 4. Thus, for every three rows, (nequals 3) of repeating pixel patterns, 4 scan lines (3 plus 1) areneeded to activate every three rows. A 3×4 pixel unit cell (3 rows by 4columns) 336 and provides EMI correction data at every third and fourthor every fourth pixel when operating in an EMI correction mode. Theaddition of the additional scan line every second row decreases thepanel read-out rate to 4 scan lines/3 rows or 1.33× slower than theoriginal panel read out rate. The pitch of pixel unit cell used in anEMI correction mode in FIG. 9 equals 4 scan lines multiplied by aminimal predefined pitch of an individual pixel. In an embodiment of theinvention, the pitch of an individual pixel is 200 um, and thus, thepitch of the cell 336 is 4 scan lines times 200 um, or 800 um.

Referring now to FIG. 9, the detector display portion 320 includespixels 322, 324, 326, and 328 binned in repeating patterns across threerows and four columns as shown in pixel unit cell 336. An additionalscan line is added after every other two rows, thereby splitting everyother two rows of the detector portion 320 into two row segments shownin FIG. 9. An unlimited number of rows may be defined by a repeatingpattern of non-split rows, in combination with split rows in betweenevery two non-split rows. A first, and a second scan line activates thefirst non split row, a second, and third scan line activates the secondnonsolid row, the third and a fourth scan line activates the split rows.

As shown in FIG. 9, a first set of pixels 322 and 326 is arranged in arepeating pattern of three pixels 322 and one pixel 326 on selectedrows, wherein pixels 322 are associated with a first respective scanline (scan lines a, and d, respectively), and pixels 326 are associatedwith a second respective scan line (scan lines b and e, respectively)adjacent to the respective first scan line (scan lines a, and d,respectively), a second set of scan pixels 326 and 328 is arranged in arepeating pattern of two pixels 326 and two pixels 328 on selected rows,wherein pixels 326 are associated with a second respective scan line(scan lines b, and e, respectively), and pixels 328 are associated witha second respective scan line (scan lines c1 and f1, respectively)adjacent to the respective second scan line (scan lines b, and e,respectively), a third set of pixels 324 and 328 are arranged in arepeating pattern of one pixel 328 c, and three pixels 328 on selectedrows associated with two scan lines, wherein pixels 328 are associatedwith the third scan line (scans line c1, and f1, respectively) adjacentto the second scan line (scan lines b, and e, respectively), and whereinpixels 324 are associated with a fourth scan line (scan lines c2 and f2,respectively) adjacent to the third scan line (scan lines c1, and f1,respectively). The fourth scan line (scan lines c2 and f2, respectively)splits the pixels 324 and 328 in half, and thus splits every other rowinto row segments.

A plurality of FETS are associated with each of the pixels 322, 324,326, and 328. Each FET, illustrated as enlarged rectangular dots withina particular pixel, respectively associated with each pixel 322, 324,326, and 328 are each associated with a particular scan line. Asillustrated in FIG. 9, pixels 322 are associated with the first scanline (scan line a, and d, respectively), pixels 326 are associated withthe second scan line (scan line b, and e, respectively), 328 areassociated with the third scan line (scan line c1, and f1,respectively), and pixels 324 are associated with the fourth scan line(scan line c2, and f2, respectively).

The repeating arrangement of the binned pixels 322, 324, 326, and 328forms the 3×4 pixel unit cell 336 that is repeated over the entirepanel, wherein the rows a, b and d, e are not split by a scan line, butthe rows c and f are split by a scan lines, thus forming row segments c1and c2, and c1 and c1, respectively. Row segments c1 and c2 form row c,and row segments f1 and f2 form row f. Rows a, b and d, e are activatedwhen scan lines a, b and d, e are energized. Rows c and f areselectively activated, respectively when both scan lines c1 and c2, andwhen both scan lines f1 and f2, respectively are selectively activated.

Row segments c1 and f1 are selectively activated, respectively when scanlines c1, and f1 are selectively activated, and row segments c2 and c2are selectively activated when scan lines c2, and f2, respectively areselectively activated.

In an embodiment of the invention, the detector portion 320 operates ina binned normal, non-EMI correction mode (binned normal mode). Whenoperating in the binned normal mode, three rows are activatedsimultaneously by four adjacent scan lines. As shown in FIG. 9, tosimultaneously activate adjacent rows, a, b, and c, and d, e, and frespectively, four scan lines a, b, c1, and c2, associated with rows a,and b, and c, four scan lines d, e, f1, and f2, associated with rows d,e, and f, respectively are simultaneously energized. The readout rate ofthe panel would be 1× of the original panel readout rate due to fourrows being read with only a portion of the data total being read fromeach of the four rows.

When the detector portion 320 operates in an EMI correction mode, eachscan line is activated separately. Thus, scan lines a, b, c1, and c2 areactivated separately, and are each simultaneously read out on each setof four data lines (1-4, 5-7, . . . dataodd-dataodd+3,dataeven-dataeven+3) that correspond to the pixels within each pixelunit cell 336. When selectively activating scan lines a, b, and d, eeach set of repeating pixels forming pixel cell 336 in each row are readto four sets of data lines, the pixels 322 a in row a are read to datalines 1-3, and pixels 326 a are read to data line 4 to providecalibration data for pixels 322 a, and the pixels 322 d in row d areread to data lines 1-3, and pixels 326 d are read to data line 4 toprovide calibration data for pixels 322 d, respectively. The pixels 326b in row b are read to data lines 1-2, and pixels 328 b are read to dataline 3-4 to provide calibration data for pixels 326 b, and the pixels326 e in row e are read to data lines 1-2, and pixels 328 e are read todata line 3-4 to provide calibration data for pixels 326 e,respectively. Similarly, when selectively activating scan lines c1, andf1, respectively, pixels 328 (formed from pixel portions 328 c 1 and 328c 2) associated with row segment c1 are read to every fourth data line(data line 1, data line 5) and pixels 324 (formed from pixel portions324 c 1 and 324 c 2) are read to every other three data lines (datalines 2-4, and data lines 5-7) to provide calibration data for pixels328 associated with row segment c1, and pixels 328 formed from pixelportions 328 f 1 and 328 f 2 associated with row segment e1 are read toevery fourth data line (data line 1, data line 5) and pixels 324associated with row segment f1 are read to every other three data lines(data lines 2-4, and data line 5-7) to provide calibration data forpixels 328 associated with row segment f1. When selectively activatingscan lines c2, and f2, pixels 324 (formed from pixel portions 324 e 1and 324 e 2) associated with row segment c2 are read to every otherthree data lines (data lines 2-4, and data line 6-8) and pixels 328associated with row segment c2 are read to every fourth data lines (dataline 1, data line 5) to provide calibration data for pixels 324associated with row segment c2, and pixels 324 f 2 in row segment f2 areread to every other three data lines (data lines 2-4, and data line 6-8)and pixels 328 in row segment f2 are read to every fourth data lines(data line 1, data line 5) to provide calibration data for pixels 324associated with row segment f2.

However, all the modes of operating and reading the panel available forthe double scan line arrangement shown in FIGS. 6-7 are not availablefor the 3×4 pixel unit cell design.

In an embodiment of the invention, shown in FIG. 9, a 3×4 pixel unitcell design is shown. The panel having the 3 by 4 pixel cell arrangementcannot be read at an original speed and resolution, wherein an originalspeed and resolution is the read out speed and resolution of thedetector that occurs when no EMI correction data is present.Additionally the panel shown in FIG. 9 cannot be run in a binned modewith EMI correction data because of the asymmetric arrangement of thepixels and scan lines throughout the panel. However, a 3-row binned modewith no EMI correction having the pixel architecture shown in FIG. 9 maybe performed using the panel arrangement shown in FIG. 9, thus allowingthe detector to read at a normal 1× operating speed.

In FIG. 9, an additional scan line is only added at after every thirdrow, wherein n equals 3, and wherein the number of scan lines equalsn+1, or 4. This results in a 3×4 pixel unit cell and provides EMIcorrection data at every fourth pixel. The scalar factor that increasesthe total time to read-out the panel is 4/3 or 1.33×.

FIGS. 10-13 disclose embodiments of the invention that add additionaldata lines instead of additional scan lines, wherein the FETs associatedwith each unit cell 450 is attached to every other data line, whereinonly one of the two data lines is operably coupled to each pixel.

As shown in an embodiment of the invention FIG. 10, the additional datalines separate each pixel photodiode into two portions, and the FETs areattached to the data lines in alternating arrangements similar to thearchitecture shown in FIGS. 6-7, wherein the data lines and the scanlines are transposed and wherein the pixel unit cell is defined by thelocation of the FETs within each pixel and repeating patterns of thepixels.

FIG. 10 illustrates an embodiment of the invention showing selectedpixels 402 of a detector portion 400. FIG. 10 is plan view of a portionof a flat panel detector 340 with detector portion 400 having dual datalines 404 a, 404 b shown in accordance with an embodiment of theinvention.

The FET 408 a associated with a pixel 402 a is coupled to and read outon scan line 404 a, and the FET 408 b associated with pixel 402 b isrelocated within the pixel 402 b (shown in the middle of pixel 402 b inFIG. 10) to couple with and to read out on data line 404 b.

The detector portion 400 adds extra data lines 404 b instead of extrascan lines 40 b as shown in FIG. 4. As with the extra scan lines 40 b inshown in FIG. 4, the extra data 404 b lines run through the middle ofeach pixel 402 a, 402 b in order to minimize shorts between the datalines 404 a, 404 b and common electrode 406. The photodiode material isremoved under the new data lines 404 b in order to minimize capacitance,capacitive coupling, and noise. A conductive bridge 482 electricallycouples diodes 412. Scan lines 420 are used to activate the FETs 408 a,and 408 b.

Thus, each data line 404 is connected via a FET 408 to a selectedportion of the pixels in each associated column 410. Since each pixelwithin the detector must be connected to a data line 404 in order toproperly read out to the readout electronics, the remaining pixels mustbe connected to an adjacent data line.

The new data line 404 b that runs through a portion of the pixel unitcell 450 reduces the potential of shorts between the respective scan ordata lines. In order to minimize the capacitance of the new scan or dataline and the capacitive coupling to each photodiode, the photodiodematerial above the new data line 404 b is eliminated. Each splitphotodiode 412 a, 412 b includes an associated conductive bridge 482 a,482 b, respectively or contact linking the cathodes 474 a, 474 b of eachof the split photodiodes together. The conductive bridge 482 a, 482 bincludes a conductive material such as a metal and connects two portionsof each photodiode 412 a, 412 b across the additional data line 404 b.An additional via 465 a, 465 b, respectively connects a common electrode406 to both portions of each the split photodiodes 412 a, 412 b,respectively.

FIG. 11 is a block diagram and schematic of a pixel architecture in adetector device having two data lines associated with each column ofpixels in accordance with an embodiment of the invention. Moreparticularly, FIG. 11 is a schematic of a portion 400 of the electriccircuit forming the detector 340 having the pixels 402 a, and 402b-defining the pixel unit cell 450 arranged in alternating patterns ofFETs 408 a and 408 b, respectively associated with diodes 412 a, 412 bthroughout the detector 340 in accordance with an embodiment of theinvention. The FETS 408 are activated by associated scan lines 420 andare read out to each data line. The schematic of the additional dataline pixel architecture is the similar to the architecture shown in FIG.5.

FIG. 12 is a schematic of a pixel architecture of a portion of adetector 340 with a 1×2 pixel unit cell illustrating a double data lineconfiguration associated with every column of pixels in accordance withan embodiment of the invention. In an embodiment of the invention shownin FIGS. 12-13, every other FET 408 is connected to a new data line 404a thereby resulting in a 1×2 pixel unit cell pattern 342 formed ofpixels 344 and 346, wherein pixels 344 are formed from two pixel portionand wherein pixels 346 are formed from two pixel portions that arerepeated across the entire detector panel. Similar to the design of therows of pixels associated when additional scan lines are added, thediodes 412 within each column of pixels are split by the data lines,wherein two data lines are associated with each pixel in each column,and wherein the each of the columns a-d, are formed from column segmentsas follows: column segments a1 and a2 form column a, column segments b1and b2 form column b, column segments c1 and c2 form column c, andcolumn segments d1 and d2 form column d. Scan lines 1-4 sequentiallyactivate each of the rows in detector 340.

FIG. 13 is a schematic of a binned pixel architecture of a portion of adetector 348 with a 1×4 pixel unit cell 350 illustrating a double dataline configuration associated with every column of pixels in accordancewith an embodiment of the invention. A block diagram schematic of adetector portion 348 shown in FIG. 13 in an embodiment of the invention.In an embodiment of the invention shown in FIG. 13, FETs associated withpixels 344 and 346 are arranged in alternating patterns in pixel unitcells 350 throughout the detector portion 348, wherein each FET isconnected to either a first or a second data line in each column. The1×4 pixel unit cell 350 allow 2-pixel binning to increase the read-outrate of the panel, in a similar manner to the detectors disclosed inFIGS. 6-7.

In addition to EMI correction, all designs described also haveadditional applications for correction of image artifacts. Correctiondata is also available on adjacent pixels on a given column as well ason a given row. While this information is not generally useful for EMIcorrection (since it occurs at earlier and later times) it can be usedto perform corrections for other phenomena that vary more slowly overtime. Examples of these phenomena include: leakage signal generated byall the other “off” FETs on the same data line, capacitive couplingartifacts associated with reading a flat panel x-ray detector while itis being exposed by x-rays, current induced during vibration or bendingartifacts, and triboelectric currents generated in nearby conductors orinsulators when the digital detector is mechanically stressed.

The above-described steps are meant to be an illustrative example; theoperation of the detector may be performed synchronously, sequentially,simultaneously, or in a different order depending upon the application.

The present invention provides multiple x-ray detectors that may beapplied in various applications. The x-ray detectors have varying pixelarchitectures including varying degrees, levels, and quantities ofresolution, pixel unit cells, pixel connection pitch, scan driverchannels, readout circuitry channels, noise performance, data linecapacitance and resistance, power consumption, and heat generation. Thedetectors of the embodiments of the present invention provide a dualfunction x-ray detector capable of operating in a normal operation modeor in an EMI correction mode in accordance with multiple embodiments ofthe present invention.

While only certain features of the invention have been illustrated anddescribed herein, many modifications and changes will occur to thoseskilled in the art. It is, therefore, to be understood that the appendedclaims are intended to cover all such modifications and changes as fallwithin the true spirit of the invention.

1. A detector device comprising: at least one pixel having a photodetector portion and a non-photodetector portion; a first line for operably coupling to each of the portions of the pixel; a second line arranged to separate a portion of the at least one pixel, wherein the second line is not operably coupled to the at least one pixel; and wherein the first line is selectively enabled to selectively activate the photodetector portion.
 2. The detector device of claim 1, wherein the photodetector portion comprises: two photodiodes coupled in parallel and separated by the second line; wherein the non photodetector portion activates the two photodiodes to store a charge in response to a signal received by the first line.
 3. The detector device of claim 1, further comprising: at least two pixels forming a pixel unit cell, the at least two pixels each having a photodetector portion and a non-photodetector portion, wherein the first line selectively activates the photo detector portion of a first pixel of the at least two pixels and the second line selectively activates the photodetector portion of a second pixel of the at least two pixels; wherein at least one of the two pixels communicates a signal representing charge stored within the photodetector portion to an associated data line after selective activation of the first line, and wherein at least one of the two pixels communicates electromagnetic interference (EMI) correction data to an associated data line to correct EMI in the other of the at least two pixels after selective activation of the second line.
 4. The detector of claim 3, further comprising: a plurality of pixels each having a nonphotodetector portion defined by a FET and photodetector portion defined by a photodiode; a plurality of scan line coupled to a selected number of FETs associated with selective portions of the plurality of pixels, wherein portions of the scan line couple to gates of a selected number of FETs to activate the FET; and a plurality of data lines coupled to a selected number of FETs in series with the photodetector portions to read-out a charge stored within selected photodetector portions to associated read-out electronics.
 5. The detector device of claim 1, further comprising: a plurality of first and second lines.
 6. The detector of claim 5, further comprising: two scan lines in signal communication with at least two data lines.
 7. The detector device of claim 1, further comprising: a third line operably coupled to each of the photodetector and non photodetector portions to read a signal representing charge stored in the photo detector portion in response to activation of the photo detector portion of the first line.
 8. The detector of claim 1, further comprising: a FET defining the non photodetector portion.
 9. The detector of claim 1, wherein the second line is electrically insulated from the at least one pixel.
 10. An x-ray detector device comprising: a plurality of pixels including a photodiode portion and a FET portion for receiving x-ray signals; at least one scan line coupled to at least a first portion of the pixels for selectively activating at least a first portion of the pixels; at least one data line for conducting charge indicative of the x-ray signals; a second scan line operably coupled to at least a second portion of the pixels for selectively activating at least a first portion of the pixels, wherein the second scan line is not operably coupled to the at least second portion of the pixels; and, a second data line for conducting charge indicative of the x-ray signals from at least the second portion of the pixels.
 11. The x-ray detector device of claim 10, further comprising: a plurality of pixel unit cells arranged in a repeating pattern, wherein each unit cell is defined by n by m pixels, and wherein n defines a number of rows and m defines a number of columns associated with each unit cell.
 12. The x-ray detector device of claim 10, further comprising: a plurality of scan lines each associated with a portion of pixels in respective rows of pixels, wherein a total number of n rows exists for each repeating pattern of portions of the plurality of pixels defining a pixel unit cell; and, a plurality of data lines in operable communication with the plurality of scan lines.
 13. The x-ray detector of claim 12, wherein a total number of scan lines equals n+1.
 14. The x-ray detector device of claim 12, further comprising: a selected portion of the pixels defining calibration pixels, wherein every n+1 pixel along a respective row direction forms a respective calibration pixel that communicates calibration data to at least a portion of the plurality data lines.
 15. The x-ray detector device of claim 12, further comprising: a predefined pitch of the pixel unit cell defined as a number of scan lines necessary to activate the pixel unit cell multiplied by a minimal predefined pitch.
 16. The x-ray detector device of claim 12, wherein the plurality of pixels are arranged in respective rows and columns within each pixel unit cell wherein selective rows of said plurality of pixels are coupled to double scan lines when n equals 1 and wherein a total number of scan lines associated with each pixel unit cell is equal to n+1.
 17. A method for operating an x-ray detector comprising: simultaneously acquiring image and electromagnetic inference (EMI) correction data during an acquisition; and operating the detector in either a normal operating mode or in an EMI correction mode.
 18. The method of claim 17, further comprising: disabling collecting EMI correction data during the acquisition.
 19. The method of claim 17, further comprising: using the EMI correction data to suppress EMI from the detector.
 20. The method of claim 17, further comprising: binning a plurality of pixels within the detector in a symmetrical distribution of pixels within each pixel unit cell to achieve optimal EMI correction when operating in an EMI correction mode. 